Operation0515−1/A1
Winterthur Gas & Diesel Ltd.
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2. Defective Fuel Pump Actuator
2.1 Fault Identification
If an actuator becomes defective, its output stays the same or changes slowly to zero
supply. The toothed rack does not change when the load changes.
At higher fuel consumption, the serviceable actuator has control of the fuel quantity
regulation.
At lower fuel consumption, the fuel pressure control valve 3.06 has the fuel pressure
regulating function.
Note: If all the actuators become defective, their regulating outputs stay in
position or turn slowly to zero delivery. The toothed rack does not change
when the load changes. Fuel quantity regulation is not possible at lower
fuel consumption. The fuel pressure control valve 3.06 has the fuel
pressure regulating function for lower fuel consumption. The fuel
quantity that flows off goes into the fuel return.
Operation with these control functions must be prevented if possible, or kept for only a
short time. Decrease the rail pressure (see paragraph 2.3 and 5562−1 Fuel pressure
control valve 3.06).
If there is an overpressure in the HP fuel system (i.e. the fuel pressure control
valve 3.06 becomes defective), the fuel overpressure safety valve 3.52 opens and the
level switch LS3426A activates an alarm.
2.2 Causes
The causes of a defective fuel pump actuator are as follows:
D The actuator is blocked.
D There is electrical interference (a cable coupling is defective, a cable is
defective etc).
2014
Faults in High Pressure Fuel System
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